The government argues such decisions will be put into the hands of parliament rather than ministers. It rejects the argument that empowering a body of 'experts' will undermine accountability on important planning issues.

Mr Betts says the secretary of state is an accountable politician, regardless of their role being quasi-judicial, and says it will only take "two or three months longer" in terms of concerns about speed.

Local government minister John Healey has written to MPs in an attempt to win them over with concessions.

He points out the new commission's remit will mainly cover the decisions currently made by the secretary of state and not those made by local authorities.

But an early day motion on the issue has already attracted the support of at least 63 Labour rebels, suggesting enough may be listening to Mr Betts' arguments rather than the government's.

He rejects the 'rebel' tag and says, having been away for the last week, he does not know how much support his amendment will attract.

"I'm in general supporting the bill - it is just this bit of it which is very badly wrong," he added.

"At this stage there's a small number of MPs," he said. "But there are a lot of people generally concerned with the planning bill. I just hope the government will give way."